How can you tell whether a molecule is covalent or ionic?

if a molecule is a covalent bond, the atoms involved in this covalent bond equally share the electrons located in their electron shells, respectively. An example of this is a hydrogen bonding. In other words, electrons in both atoms are equally in the affinities of the others. However, an ionic molecule is usually an unbalanced entity. One atom may be more electronegative than the other and thus cause the electrons of other atoms to come to the affinity that it holds. Thus, an ionic molecule would look like a small atom that would be bonded to a bigger one.